reinyHow do I find a variance for a set of numbers {1,16,8,17,12} I got that variance-34.2, but I'm unsure. Any help? Thanks. math - Reiny, Sunday, January 24, 2010 at 8:16pm look at his page. Reiny - April, Sunday, January 24, 2010 at 8:25pm I looked at that page and did my ...
January 24, 2010 by April

AlgebraI have an exponent properties test tomorrow, its our last one before the final, so its important, but anyways, there is one question on the review that is confusing me. Could you please help? Here it is : (2y2x7)(-xy)(9x-3y) I dont know if the exponents showed up, but the ...
January 6, 2011 by Abigail

Reiny! Reiny! Reiny! Answer Check and HW Help!Translate to a system of equations and solve: 1) The sum of two numbers is 36. One number is 2 more than the other. Find the numbers. Answer: (17,19) 2) Find two numbers whose sum is 66 and whose difference is 18. Answer: (37,29) These ones I am not sure of: 3) The difference ...
February 12, 2009 by Britney

Reiny! Reiny! Reiny!1. Oanh walked from her home to the grocery store at 3 mi/h and jogged home at 6 mi/h. Her total round trip was 15 minutes (1/4h). How far from Oanh's home is the grocery store? (use an equation to solve this) Help, I am totally clueless on this.
February 5, 2009 by Ellen

CalculusWhat is implicit differentiation...as in what would be the steps in solving it. I read my textbook but it seems very confusing. 1) Differentiate both sides with respect to x 2) Realize that y is a function of x 3) Solve for y Plus the d/dx notation made it even more confusing...
November 4, 2009 by Nikita

MathTo Reiny: Hi, thank you for your time Reiny and your info. I am so sorry but on the first one I accidentally put 0 where I should have put =9. In other words, the first equation should have said (9n+1)squared =9. Really sorry to have taken up your time with the wrong equation...
November 3, 2013 by Brandi

Math (need more help Reiny)Ok i figured out the first part that i need to square the numbers so after 4 it will be 5x5,6x6,7x7,8x8and 20x20 to make up the second column, what i dont get is the 3rd one, how do i come up with the number of white triangular shapes used?
June 25, 2009 by Keira

MathEvaluate:|12 5 -2| |-3 0 1| |-5 4 2| It's going to be really confusing if I post my work. I got -127 from all the confusing things I did
February 26, 2008 by Jon

Urgent math question for ReinyFind the value of the expression below for r=4 and t=2.... t^3-r+20 divided by r 9*** 72 6 40 Ok, Reiny you said my answer9 was originally wrong, however when I looked at the work you did and you put in parenthesis()....my question is why, because the original expression didn'...
September 4, 2013 by Gabby

Math-Reiny this one is more confusing to me :(A survey of vegetable gardeners showed the following: 63 grew tomatoes 26 grew cucumbers 38 grew zucchini 18 grew both tomatoes and cucumbers 22 grew both tomatoes and zucchini 19 grew both cucumbers and zucchini 14 grew all three types 18 grew none of these three (a) How many...
July 11, 2011 by Jen

MathI understand how to do these kind of problems except this one. Write the equation that has the given roots. Roots: 3 with multiplicity of 2, -5, 0 with multiplicity of 4. By the way I understood the help that I got earlier, but this problem seems to be more confusing.
May 13, 2010 by Jennifer

math helpThank you for helping me with the last problem Reiny and Bosnian. However, I have one more problem that I need help with please and I have no idea how work the problem. I used an on line calculator to get the answer. It didn't give an explanation on how to do the problem ...
April 23, 2012 by Urgent Urgent Please

URGENT~MATH For Steve or ReinyFor questions 5-7, find the solution to the system of equations by using either graphing or substitution. 5)y=6-x and y=x-2 (1point) (2,4) (-4,2) (4,2) no solutions 6)y=2x-1 and y=x+3 (1point) (4,7) (7,4) (-7,-4) no solutions 7) y=4x and y+x=5 (1point) (-4,1) (1,4) (-3,2) (2,3...
May 7, 2013 by Gabby

Math: Reiny I already posted this question, and Reiny had a question about the question. How many square units are in the region satisfying the inequalities y>=(x) and y<=-(x)+3? Express your answer as a decimal. * the () are absolute value signs. Math - Reiny, Wednesday, December ...
December 3, 2014 by Jenny

reinythanks reiny--but i'm in 6th gr and we r not studying powers..can you help me with a simpler answer without powers?
November 12, 2009 by jane

mathhow I change 28/9 to a mixed or whole number divide 28 by 9 to give you 3 with a remainder of 1. so 28/9 = 3 1/9 (three and one ninth) Thank you Reiny
March 12, 2007 by carmen

algebraBut I am getting more and more confused. -3-3x=-9????? and x/6=-24 but the there is a negative sign like x - - =-24 6 I know I am over thinking this,but I am confusing myself on these two???
August 19, 2013 by jan

Calculus--ReinyCalculus - Reiny, Friday, December 23, 2011 at 6:59pm I read that as (4a^2-1)/(4a^2-16) * (2-a)/(2a-1) , my brackets are necessary = (2a+1)(2a-1)/( 4(a+2)(a-2) * (2-a)/(2a-1) the (2-a)/(a-2) are opposite, they will give you the -1 so.. = -(2a+1)/(4(a+2)) , again you have to ...
December 25, 2011 by -Untamed-

Reiny!!!! math helpWe understand how to do the questions now and we are really glad n thankful, but the graphing portion of it is confusing. Continuation of the function. The teacher wants us to plot the points from the different parts of the questions we answered and with your help we graphed ...
October 9, 2012 by Cole n Cynthia

Thank you Jiskha and ReinyI just wanted to write a post to thank everyone who helps out. I haven't found people to be very grateful on this site so I thought i'd take a moment to tell you how awesome you guys are. Special thanks to Reiny for all the helpful math tips. You have helped me through a lot ...
January 17, 2013 by Anonymous

Algebra-Reiny please explain thisHi Reiny, I posted this problem earlier and you responded but I don't get the reasoning- The problem was -2log8(x+1) = -8 you said multiply by -2 and then you put log8(x+1)=4(wasn't that dividing by -2) log8(x+1)^2 = 8 (how did you get to the power of 2 and =4 became =8 x+1 = ...
December 13, 2010 by Anna

englishhow does shifting the point of view [third person to first person] change the effect on the reader It's very confusing. If a story or essay starts out in 3rd person, the reader picks up on that and expects that to continue -- a shift to another POV is confusing and could lead ...
April 16, 2007 by jamey

Pre Calc (For Reiny)Thanks so much your method worked perfectly! My solution was: the remaining zeros were 5+2i, 3, and -4 I have one question that's bugging me though, why is it that synthetic division did not work for me? I thought that long division and synthetic division were both ...
November 15, 2009 by Zach

MATH (to Reiny)I tried to simplify it with the second fraction by multiplying the top and bottom by "r" and i didn't work. Well at least I don't understand how to get there. Can you please just explain how... n!r/(n-r-1)!(r-1)!r goes to n!r/(n-r+1)!r! I get one put of it, that r x (r-1)! = r...
March 4, 2009 by Alex

MathMrs. Hart, at age 65, can expect to live for 25 years. If she can invest at 5% per annum compounded monthly, how much does she need now to guarantee herself $900 every month for the next 25 years? math - Reiny, Friday, April 3, 2015 at 3:05pm Present Value = 900(1 - 1.0041666...
April 3, 2015 by Judy

7th Grade MathI do know how to find the area of a square and rectangle, but how do you fing the area of a rhombus. (that is at least what it looks like.) The shape I'm talking about is like a rectangle but it looks like one side got stretched to the left. (sorry if I made that even more ...
February 15, 2013 by Jessie

7th grade-Algebra Worth ProblemPlease show equation and solve for the following 1. Lyn's age is 8 years less than 15 times the age of her niece Elizabeth. If the sum of their ages is 24, what is Elizabeth's age ( Let e= Elizabeth's age) 2. Bob is renting a canoe for $20, plus $9.75 per day. How mant days ...
September 23, 2009 by DMAR

Math( Attn: Reiny)1. A rental business charges $12 per canoe and averages 36 rentals a day. For every 50-cent increase in rental price, it will lose two rentals a day. What price would yield the maximun revenue? I was told the answer by Reiny, but I couldn't get the right answer. I found the ...
January 25, 2015 by Wendy

Pre-Calculus - ReinyReiny you helped me with this logarithm yesterday: How did you write it out as log2 ( √A / B^3 ) Laws of logarithms combine, write as a single logarithm Need help on this question please, Im stuck, dont know where to go abouts from here: I did it on paint and uploaded it...
October 17, 2012 by Shreya

mathan estate valued at $62,000 is left by a will as follow:to each of two grandchildren a certain sum,to the son twice as much as to the two grandchildren together,and to the widow $2,000 more than to the son and granchildren together. How much goes to each? I tried by reading ...
September 16, 2010 by Kaylen

MathDear Reiny! U r a life-saver! Is there a short cut to how can I set the question or change word problems into math one? It seems that this is my problem! Also, why did my way worked as well with different answers? My answers satisfied all equations as well. Many thanks.
April 9, 2010 by Me

3 grade math ms sueName the lengths of the sides of three rectangles with perimeters of 12 units. Use only whole numbers. My son did -2-4-2-4 And one more 1-5-1-5 And one more 3-3-3-3 And I need one more rectangles number how you can make
March 8, 2012 by Dw

TO REINYThank you Reiny, Why I have to divide 632/1.05? I was dividing 632/0.05, I need to understand for future similar problems, I really appreciate your help, I finished school almost 30 years ago, I decided to go back to school an obtain a degree, I try my best but so many years ...
January 25, 2015 by maribel

mathTo find the weight of the gold in a 22 karat gold object, multiply the object's weight by 0.917. To find the weight of the gold in an 18 karat gold object, multiply the object's weight by 0.583. A 22 karat gold statue and a 14 karat gold statue both weigh 73.5 ounces. Which ...
October 22, 2014 by Kymy

mathIf it says: "five less than three times a number is 20 More than half a number" would the equation be 3n-5=n/2+20? If so what would the answer be? Please help this is a bit confusing!
January 6, 2014 by jeffery

10th grade math1.548937075 x 10 to the 12th. round the number to 3 significat figures. I thought I would respost this because the other one was getting confusing
August 19, 2008 by Rebekah

mathThis is a confusing problem to me also, can someone please help me? What are the odds in favor of getting at least one head in three successive flips of a coin?
October 9, 2009 by Aleah

mathAn equation is not a function if even one x value produces ____ corresponding y value(s). one less than one more than one zero for a my guess is more
February 3, 2015 by Elena

dr bobI am still confused by the last one CO3^2- You were nice enough to do a diagram and then the expalnation for what else I needed to do was so confusing - I am at study hall and this is my last one
December 14, 2007 by sam

GrammarA simple sentence: A) Can be reversed and still mean the same thing. B) Expresses one complete thought with one subject and one predicate. C) Expresses one or more complete thoughts with one or more subjects and one or more predicates. D) Is easy to understand. My answer is C
December 12, 2012 by Marie

Physics II have this vector that is confusing me I know what I need to do but the components of these vectors are confusing me. Problem: You are standing at point with coor dinates (1m, -1m, -2m) another erson is at r(t)=(8m)i - (3m/s^3) t^3 j + (4m/s^2) t^2 k Find distance between you...
March 18, 2011 by David

Chemistry .50 - x / x = 3.20e-1 I need to solve for x. I was going to do .50 X 3.20e-1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help) - Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50 - x)/x...
April 23, 2012 by Hannah

Reiny or Damon or Bobpursley Express the series 11 + 18 + 27 +...+ 171 using sigma notation. Usually you would take 27-18 and thats the step between numbers, right? (I think its the k-value?) But 27-18=9 and 18-11=7. Are we stepping by k+2 here? Like k, k+2 k+4, k+6...? Please help me. I'm not confident ...
April 27, 2012 by Tabby

Chemistry(Please check).50 - x / x = 3.20e-1 I need to solve for x. I was going to do .50 X 3.20e-1 and then take the square root but this is not correct. I am not sure what to do. Thank you for your help. Math(Please help) - Reiny, Tuesday, April 17, 2012 at 3:18pm You probably meant (.50 - x)/x = ...
April 19, 2012 by Hannah

health Please help as this is so confusing tome! 25. In addition to the nucleus, cytoplasm, and cell membrane, a single neuron possesses A. one dendrite and several axons. B. several dendrites and one axon. C. many nuclei and one neurilemma. D. one nucleus and many neurilemma.
June 28, 2010 by Jackie

mathOrder of Magnitude (I'm not quite understanding it) 1) trying to 0.0000000734 estimated as the product with a single digit power of 10.*No multiple choice* 2) Trying to find the numbers that a greater than 7 x 10^-4 (Choose more than one answer type question) - 8 x 10^-4 * my ...
September 8, 2014 by Anonymous

maththanks reiny for the help but can u tell me the domain of f g and fog in binary form? thanks
October 26, 2010 by mary

MathI need to change this number to a percentage, rounded to the nearest tenth. 1350-1010/1010=.336633663 would the answer be 3%? this one is confusing to me for some reason
March 30, 2010 by Amy

German help - Reiny#3 was supposed to be.... Mutters und Vaters Kinder sind A. meine Cousins B. mein Geschwister C. meine Schüler. D. meine Geschwister.***** This is the one I typed wrong last night - sorry about that...not sure on this one but I chose D....? Thanks for your help
February 13, 2014 by Cassie

mathThanks for the answer Reiny, could you explain the way you solved the factor of 21y^2+38+5
April 26, 2011 by lori

MathReiny can you show me how to check this problem. 5a^8-20a^7-25a^6 =5a^6(a^2-4a-5) =5a^6(a^2-5a+a-5) =5a^6(a(a-5)+1(a-5) =5a^6(a-5)(a+1) (answer)
July 26, 2011 by Ms.Ellis

mathIn a pseudopythagorean triangle, the sides are all integers and the sum of the square roots of the sides equals the square root of the third side. How many pseudopythagorean triangles are there. A. none B. 1 C. 2 D. more than 2 this is such a confusing question
July 30, 2015 by Ryan

Math - OddsIf you toss three coins, what are the odds in favor of getting exactly two tails and one head? A. 3:8 B. 3:5 C. 5:3 D. 8:3 can you explain this? i can do odds but this is confusing me.
May 28, 2013 by bubbie

mathhow are and 3 4th bours and the distance traveled in 2 3 4th hours represented in the table?how are they shown on the graph? Having read the next four or five posts, I suggest you do two things: 1. Start over and write a complete question for each post. Fragments of questions ...
October 2, 2006 by chemiii

Algebra I already posted this question and Reiny answered it, I just wanted to clarify my answer Problem: If f(x) is a polynomial of degree 4, and g(x) is a polynomial of degree 2, then what is the degree of polynomial f(x)-g(x)? Reiny: so f(x) has to contain an x^4 term and g(x) does...
November 12, 2014 by Trish Goal

Morse Code Please Answer!My book doesn't explain how, for example, if D was --. and O was .-. than how would they tell the end of the D from the beginning of the O? Did they pause between letters? But then how would they know the difference between a "new letter" pause, and a "new word" pause. Could ...
February 22, 2007 by Jenna

HomeworkWe, my roomates and I, keep getting replies saying stop posting under more than one name. We are not posting under more than one name we are all different. We all live together and only have this common computer at the moment, but we are more than one person and we love this ...
November 12, 2007 by Olivia

math (Reiny)If # (a,b,c,d)means you raise b,c and d to the power of a and then take the sum of the resulting values, and # (2,3,4,d)=89,then d=? 2^a + 3^a + 4^a = 89 1^a + 1^a + 1^a = 89 3^a = 89 a = 86 an I do it right
December 19, 2013 by peter

Algebra III solved one of these sigma notations and had Reiny check it in an earlier post but this one totally befuddles me- Which of the following terms would not be in the series generated by the expression: 5 Signma symbol (k^2-5k+2) k=2 the choices are 2, -2, 4 or -4If you could ...
December 5, 2011 by Julia

Trig.......I need to prove that the following is true. Thanks (2tanx /1-tan^x)+(1/2cos^2x-1)= (cosx+sinx)/(cosx - sinx) and thanks ........... check your typing. I tried 30º, the two sides are not equal, they differ by 1 oh , thank you Mr Reiny I'll tell my teacher this Question is Wrong...
April 18, 2007 by abdo

mathyou have one penny one nickel one dime and one quarter. how many different amounts of money can you make using one or more of these coins ... please help..me..:(
December 9, 2009 by Katherine

ap biology againIn order to answer a question I must use this information but I find it very confusing. The restriction enzymes of bacteria protect the bacteria from succesful attack by bacteriophages, whose genomes can be degraded by the restriction enzymes. The bacterial genomes are not ...
January 4, 2008 by claudia

Biology - fossilsmy sister Shreya be sick so i posting her biology questions. one question ask hw did creationists explain fossils. she write this be about noah's flood but what be noah's flood? i look up on internet for her and there be too much confusing words. i only be able to make out ...
March 2, 2012 by Mohammad

Reiny Or Damon?Thanks for reading this! A triangular prism has vertices at A(2,-1,-1) B(2,1,4) C(2,2,-1) D(-1,-1,-1) E(-1,1,4), and F(-1,2,-1)? This question has two parts: 1 - Which image point has the coordinates (-3,2,1) after a translation using the vector <-5,1,3> I'm thinking it'...
April 26, 2012 by For Reiny

mathmultiply the equation by a power of 10 to write an equivalent equation with integer coefficients: #1. 4.15x+3.01=10.9x+1.29 #2. 1.596y-3.08=0.9y this is the 2nd time I'm posting this question. but the last reply I got was confusing. can you please show me how to do at least ...
September 21, 2009 by Anonymous

Reiny Damon Bobpursley?Thanks for reading this! A triangular prism has vertices at A(2,-1,-1) B(2,1,4) C(2,2,-1) D(-1,-1,-1) E(-1,1,4), and F(-1,2,-1)? This question has two parts: 1 - Which image point has the coordinates (-3,2,1) after a translation using the vector <-5,1,3> I'm thinking it'...
April 27, 2012 by Tabby

MathSoybean meal is 18% protein, cornmeal is 9% protein. how many pounds of each should be mixed together to get a 360 pound mixture that is 15% protein ? Word problems are my favorites, but this one is confusing me. Help is very much appreciated
July 7, 2010 by Christy

english Regarding the use of commas, which one of the following statements is accurate? A. A parenthetical use of commas is usually confusing to the reader. B. There is no need for commas that indicate added details in a sentence. C. Commas are needed to separate a list of three or ...
May 2, 2013 by selena

AccountingHow does one determine variance analysis? I am trying to understand this and my text book is confusing me. Also, to determine this, would one find the the answers in the balance sheet or cash flow statement, or from the revenue and expenses?
April 30, 2010 by Barbie

mathreiny, could you give the motorists two trips another try. it appears you can work it . i'd appriciate seeing an answer. thanks.
July 22, 2011 by mac

Math3) Find the area bounded by the curves f(x)= x^3 + x^2 and g(x)= 2x^2 + 2x. I get 4653pi/105 after help from Mr. Reiny, but this is wrong. Have I calculated incorrectly? Thank you
May 22, 2013 by Hannah

ScienceA student observed two different types of cells under a microscope. She noticed that one cell had many more mitochondria than the other. What can the student predict about the cell with more mitochondria? A. The cell produces more waste. B. The cell makes more proteins. C. The...
February 27, 2012 by Kate

factoringlet f(m)=m^3 + 3m^2 + 3m + 1 notice f(-1) = 0, so m+1 is a factor. Using division, the answer is m^2 + 2m + 1 which factors once more to (m+1)(m+1) so you have (m+1)^3 = 0 and then m = -1 Are you familiar with Pascal's triangle? Did you notice the pattern in the coefficients 1...
March 11, 2007 by Reiny

mathyou are planning to open a candy stand with your friends. you will need to buy 20 candy bars at a wholesale cost of $.30 each. you will need to buy 15 lollipops at a cost of $.05 each. How much money will you spend ALL TOGETHER? its pretty confusing :( and this one: for a ...
May 22, 2014 by triganle

to Reiny-5 = x - 3ã(x+4) 3ã(x+4) = x+5 square both sides 9(x+4) = x^2 + 10x + 25 x^2 + x - 11 = 0 solving this by the quadratic formula gave me x = (-1 }ã45)/2 or appr. 2.854 or -3.854 how did u go from line one to line 2
May 26, 2009 by to Reiny